The relationship between the parameters of respiratory and skeletal muscles in COPD

Background: It is known that COPD affects both respiratory and peripheral skeletal muscles. But the relationship of changes in the function and mass of respiratory and peripheral muscles is not well understood. Aim: to evaluate the relation between respiratory and skeletal muscles parameters in COPD patients. Methods: 86 stable patients with any severity of COPD (68 males/18 females, mean age 66,6 ± 8,7 years) were included in cross-sectional study. Maximal inspiratory pressure (MIP) and maximal expiratory pressure (MEP) were measured by body plethysmograph MasterScreen Body. Quantitative assessment of thoracic muscle cross-sectional areas (CSA) was performed on a single axial slice of the CT scan at the level of the carina. We measured the function of peripheral skeletal muscles: strength (handheld dynamometry, the chair stand test) and physical performance (gait speed (GS), six-minute walk distance (6MWD), the Timed-Up and Go test (TUG), the Short Physical Performance Battery (SPPB)). The Appendicular Skeletal Muscle Mass (ASM) was estimated using DXA, ASM index was calculated (ASM/height2). Results: Moderate and strong significant correlations were observed between respiratory muscle strength (MIP and MEP) and hand grip strength, GS, 6MWD, SPPB, duration of the chair stand test, TUG. We also identified associations (р<0,001) between ASM index and CSA of respiratory muscles (m. pectoralis (r=0,604), m. intercostal (r=0,550), m. paraspinalis (r=0,484), m. serratus anterior (r=0,574), m. latissimus dorsi (r=0,378) and their total score (r=0,673). Conclusion: There is significant relationship of quantitative and functional changes of respiratory and peripheral skeletal muscles in COPD patients.